What is gasoline?

­ ­Gasoline is known as an aliphatic hydrocarbon. In other words, gasoline is made up of molecules composed of nothing but hydrogen and carbon arranged in chains. Gasoline molecules have from seven to 11 carbons in each chain. Here are some common configurations:

H H H H H H H     | | | | | | |   H-C-C-C-C-C-C-C-H         Heptane     | | | | | | |     H H H H H H H     H H H H H H H H     | | | | | | | |   H-C-C-C-C-C-C-C-C-H       Octane     | | | | | | | |     H H H H H H H H     H H H H H H H H H     | | | | | | | | |   H-C-C-C-C-C-C-C-C-C-H     Nonane     | | | | | | | | |     H H H H H H H H H     H H H H H H H H H H     | | | | | | | | | |   H-C-C-C-C-C-C-C-C-C-C-H   Decane     | | | | | | | | | |     H H H H H H H H H H

Typical molecules found in gasoline

When you burn gasoline under ideal conditions, with plenty of oxygen, you get carbon dioxide (from the carbon atoms in gasoline), water (from the hydrogen atoms) and lots of heat. A gallon of gasoline contains about 132x106 joules of energy, which is equivalent to 125,000 BTU or 36,650 watt-hours:

  • If you took a 1,500-watt space heater and left it on full blast for a full 24-hour day, that's about how much heat is in a gallon of gas.
  • If it were possible for human beings to digest gasoline, a gallon would contain about 31,000 food calories -- the energy in a gallon of gasoline is equivalent to the energy in about 110 McDonalds hamburgers!